1. Field of the Invention
This invention relates to an dual reflector high bay lighting system or luminaire having a main reflector and an auxiliary reflector which distributes the light in a certain way to direct a first predetermined amount of light onto the floor or work area and a second predetermined amount of light above the work area. The subject invention increases the efficiency of the lighting system so that a fixture with a high intensity discharge lamp of lower wattage can be used to get substantially equal or greater lighting on the work area. Alternatively, a fixture in accordance with this invention which uses the same wattage lamp as a conventional fixture will provide a substantially greater amount of light on the work area. The invention includes a luminaire having a vertically oriented high intensity discharge lamp, a main reflector, and an auxiliary reflector mounted within the main reflector and movable vertically relative to the lamp for concentrating light in a first work area beneath the luminaire and providing a certain amount of light outside or above the first area. The invention also relates to an auxiliary reflector and bracket assembly for retrofitting conventional fixtures, and a retrofit kit for retrofitting conventional fixtures of a specific wattage, to dual reflector systems of lesser wattage.
High bay lighting fixtures are typically used in warehouses and manufacturing plants. Such lights are generally referred to as high intensity discharge (HID) lights or gaseous discharge lights. Conventional high bay lighting fixtures direct all of the light equally leaving the areas closest to the fixture too bright and the working areas furthest from the fixture too dim. In a typical warehouse, light fixtures will be between 15 to 65 feet above the floor. Most light is usually required at the working surface or floor level, not at the top of the storage racks or near the ceiling. However, the storage racks require sufficient lighting to enable workers operating fork lifts to have sufficient visibility to remove products from the racks and to store products in the racks. In order to obtain a desired level of light at the working area with such conventional fixtures, a fixture of higher wattage must be used. This creates overly bright conditions closer to the ceiling where it is not needed. In installations in warehouses where there are rows of racks of merchandise, with aisles therebetween, conventional HID lighting systems typically use 400 watt and 1,000 watt luminaires for such installations. The subject invention permits the 400 watt luminaires to be replaced with 250 watt luminaires, and in some instances, 150 watt luminaires, and the 1,000 watt luminaires to be replaced by 400 watt luminaires. When such a replacement is made using the subject invention, the amount of foot candles measured at the floor level is substantially the same, or greater, while the lighting at the top of the racks may be reduced, but is still more than sufficient for workers to be able to function. The energy savings resulting from use of the lower wattage lamps is typically between 40-65%. This results in substantial reduction of energy costs. Not only do customers benefit by a reduction in energy costs by replacing 400 watt fixtures with 250 watt fixtures, or even 150 watt fixtures, but, in installations using air conditioning or refrigeration, they also reduce the amount of air conditioning or refrigeration costs incurred by reducing the heat or kilowatt loading of the work space. Furthermore, they obtain an increase in efficiency from personnel working in a building by having an improved lighting level at the working surface.
2. Description of Related Art
Henderson Jr., et al U.S. Pat. No. 4,173,037 discloses a luminaire lamp support device in which the lamp socket is adjustably mounted on a bracket for adjustment of the socket along a substantially vertical axis. This enables adjustment of the lamp to different positions to obtain various light distribution patterns. The lamp has an outer reflector and an asymmetric inner reflector which is mounted for rotational adjustment about the vertical axis of the luminaire for producing asymmetric distribution of reflected light.
Sholtz U.S. Pat. No. 5,178,452 discloses an operating theater lamp with a main reflector which illuminates the area of operation and an auxiliary reflector having an outer diameter which corresponds approximately to the inner diameter of the main reflector and which is arranged inside the main reflector to deflect a part of the light beam at a steeper angle into the bottom of a surgical wound.
Wijbenga, et al U.S. Pat. No. 5,251,116 discloses a luminaire for creating a primary beam and a secondary beam.
Baldwin, et al U.S. Pat. No. 4,943,901 discloses a luminaire with auxiliary reflecting means for reflecting light passing through the top opening and for reflecting such light to illuminate stacked material along the edges of the aisle.
Compton U.S. Pat. No. 4,231,080 discloses a luminaire having at least three stack reflector members.
Cochran U.S. Pat. No. 1,286,535 discloses a lighting fixture having a main reflector and a stationary auxiliary reflector.
None of the foregoing prior art lamps have suggested a solution to the problem of conserving energy in HID fixtures. The cost of energy is rising significantly, and many power companies have offered inducements in the form of rebates to customers to cut down on their energy consumption. Lighting engineers have been forced to specify the use of 400 watt and 1,000 watt luminaires based on requirements to have a specified amount of foot candles at the work surface. Notwithstanding the prior art, no one has recognized the ability to shape and distribute the light pattern in such a way as to concentrate a substantial amount of light onto the work area while leaving a lesser, but still acceptable, amount of light at the middle and top of the racks sufficient to allow workmen to utilize such racks.